Plate is easy to use. It puts content first. In-context editing makes the process of editing content very intuitive, even for non-technical users. What I like about Plate is that this does not (or hardly) negatively impact the amount of control a theme developer has over the output of the site in the frontend. It strikes a very nice balance there.
Another strength of Plate is that modeling content is very easy and intuitive. It combines flexibility and structure in a very nice way, which makes it quite easy to get productive quickly.
The system is strongly oriented towards multisite environments, which is very helpful in larger organizations. Themes are developed in the cloud, which makes sure there is always one source of truth. Changes in a master theme can be propagated to all child sites with a single click.
Support from Plate is personal, helpful and fast. No matter how stuck I got, I was always able to get going again within a few hours. Review collected by and hosted on G2.com.
Plate is still a relatively new system, developed by a small company. In some areas, it misses some maturity. The documentation can be improved upon, especially for developers who are completely new to the system. The system is not hard to use, but the barrier of entry is higher than it could be because of the lack of beginner docs.
As mentioned, theme development is done in the cloud with the help of a sync tool. This works well most of the time, but it can be hard to debug issues, especially since the tools the system offers for this are quite limited. It also means that every single change a theme developer makes to a file needs to be uploaded by the sync tool before it is visible. This works well, but it always takes some time. During the span of a project, this can become a significant chunk of precious time. Review collected by and hosted on G2.com.